Knowledge about the natural history of attention-deficit/hyperactivity disorder (ADHD) is limited because most follow-up studies have been conducted on clinic samples of hyperactive, white, boys. It is not clear how relevant these data are for children identified with ADHD in community settings. In addition, little information is available about the developmental course of ADHD in girls, adolescents, African-Americans, or children with the Inattentive type of ADHD. The proposed longitudinal follow-up study will describe the natural history of ADHD in a population-based sample of children (448 with ADHD, 444 controls, and 134 borderline ADHD cases.) Between 1998 and 2000, all the elementary school children in a diverse semi-rural North Carolina County were screened for ADHD as part of an epidemiologic study. Teachers completed rating scales and parents were interviewed about their child's symptoms, medical history and life events. The proposed study will re-evaluate these same children eight to ten years later as adolescents using in-person youth interviews, parent telephone interviews, teacher rating scales, and abstracted school records. This information will be used to estimate the persistence and describe the developmental course of ADHD and its types, to estimate the risk of adverse health behaviors (smoking, drug and alcohol abuse, and accidents), to estimate comorbidity and impairment, and to evaluate whether stimulant medication treatment, as it is being administered in this community setting, is associated with improved outcomes. This study will add to current knowledge about the developmental course and public health impact of ADHD in a population based sample that includes previously under-studied populations - i.e., girls, African Americans, and children with the Inattentive Type of ADHD.